Cellular phones, smart phones and other mobile telephony devices (hereinafter, mobile phones) are becoming more and more prevalent, even to the point of replacing landline telephones for many users. Among the services that are commonly available on such mobile phones is Short Message Service (SMS), for sending and receiving short text messages to other mobile phones. SMS is a text message service that enables short messages of generally no more than 140-160 characters in length to be sent to and transmitted from mobile phones. SMS was introduced in the Global System for Mobile communications (GSM) system, and is now supported by all other digital-based mobile communications systems. The use of SMS, or “texting” as it is commonly referred to, is very popular with users of mobile phones, and is often used in a manner similar to instant messaging (IM) services available on the Internet. To send, text messages are keyed into a mobile phone keypad. Received text messages are presented on the mobile telephone's screen.
Messages are sent via a store-and-forward mechanism to a Short Message Service Center (SMSC), which will attempt to send the message to the recipient, and possibly retry, if the user is not reachable at a given moment. Messages may be Mobile Terminated (MT) or Mobile Originating (MO). Mobile Originated messages are sent from a mobile phone, and could be sent either to another mobile phone (such when a mobile subscriber sends a personal message to another subscriber) or to a computer application that will process the message. Mobile Terminated messages are transmitted to a mobile phone, and could be sent by another mobile phone or generated by a computer application.
Typically, messages are addressed to a recipient using the telephone number belonging to the recipients mobile phone. However, a portion of messages that are sent via SMS are not sent to another mobile phone as in a person-to-person communication, but are instead directed to a central location. While the central location could have a regular 10-digit telephone number as does a typical mobile telephone, SMS messages directed to a central location are often directed using a common short code address (typically referred to simply as a “short code”). A short code address is a convenient, easy to remember, short number (or text string that corresponds to a number) that identifies a central location to which an SMS message can be sent. Short codes are significantly shorter than full telephone numbers—typically four to six digits in length. Short codes are widely used for value-added services such as television voting, ordering ringtones, mobile marketing and other mobile services. SMS messages sent to short code numbers are billed by the mobile phone carriers to the mobile phone user at the same rate as SMS messages sent to another mobile phone users number or at a fixed tariff rate (“Premium SMS service”) which is made known to the mobile phone user via a required “opt-in.”